[igt-dev] [PATCH i-g-t] tests/kms_atomic_transition: Don't abuse the HSKEW flag to force a modeset

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Since kernel commit e995ca0b8139 ("drm/i915: Provide a device level
.mode_valid() hook") i915 will bluntly reject the HSKEW mode flag. Thus
we can't abuse it to force a modeset.

Since we don't particularly care about the visual results here we can
risk making the display unhappy by eg. flipping the hsync polarity
instead.

Also add a comment documenting why we're doing this.

Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104848
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 tests/kms_atomic_transition.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/kms_atomic_transition.c b/tests/kms_atomic_transition.c
index 798639393421..aa9a6f8439ea 100644
--- a/tests/kms_atomic_transition.c
+++ b/tests/kms_atomic_transition.c
@@ -410,7 +410,8 @@ run_transition_test(igt_display_t *display, enum pipe pipe, igt_output_t *output
 
 	mode = igt_output_get_mode(output);
 	override_mode = *mode;
-	override_mode.flags |= DRM_MODE_FLAG_HSKEW;
+	/* try to force a modeset */
+	override_mode.flags ^= DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_NHSYNC;
 
 	igt_create_fb(display->drm_fd, mode->hdisplay, mode->vdisplay,
 		      DRM_FORMAT_XRGB8888, LOCAL_DRM_FORMAT_MOD_NONE, &fb);
-- 
2.13.6